title: Biological properties of carotenoids extracted from Halobacterium halobium isolated from a Tunisian solar saltern.
abstract: BACKGROUND
  Bioactive molecules have received increasing attention due to their nutraceutical attributes and anticancer, antioxidant, antiproliferative and apoptosis-inducing properties. This study aimed to investigate the biological properties of carotenoids extracted from Archaea.
  
  
  METHODS
  Halophilic Archaea strains were isolated from the brine of a local crystallizer pond (TS7) of a solar saltern at Sfax, Tunisia. The most carotenoid-producing strain (M8) was investigated on heptoma cell line (HepG2), and its viability was assessed by the MTT-test. The cells were incubated with different sub-lethal extract rates, with carotenoid concentrations ranging from 0.2 to 1.5 μM. Antioxidant activity was evaluated through exposing the cells to sub-lethal extract concentrations for 24 hours and then to oxidative stress induced by 60 μM arachidonic acid and 50 μM H₂O₂.
  
  
  RESULTS
  Compared to non-treated cells, bacterial carotenoid extracts inhibited HepG2 cell viability (50%). A time and dose effect was observed, with cell viability undergoing a significant (P < 0.05) decrease with extract concentration. After exposure to oxidative stress, control cells underwent a significant (P < 0.05) decrease in viability as compared to the non-treated cells.
  
  
  CONCLUSIONS
  The bacterial extracts under investigation were noted to exhibit the strongest free radical scavenging activity with high carotenoid concentrations. The carotenoid extract also showed significant antiproliferative activity against HepG2 human cancer cell lines.
authors.affiliation: Ecole Nationale d'Ingénieurs de Sfax, UR: Etude et Gestion des Environnements Côtier et Urbain, Université de Sfax, B,P, 1173, 3038 Sfax, Tunisia. ammarenis@yahoo.fr.
authors.forename: Molka
authors.initials: M
authors.lastname: Abbes
authors.forename: Houda
authors.initials: H
authors.lastname: Baati
authors.forename: Sonda
authors.initials: S
authors.lastname: Guermazi
authors.forename: Concetta
authors.initials: C
authors.lastname: Messina
authors.forename: Andrea
authors.initials: A
authors.lastname: Santulli
authors.forename: Neji
authors.initials: N
authors.lastname: Gharsallah
authors.forename: Emna
authors.initials: E
authors.lastname: Ammar
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002338:Carotenoids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D006217:Halobacterium / Q000737:chemistry* / Q000145:classification / Q000302:isolation & purification; D056945:Hep G2 Cells; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects; D012623:Seawater / Q000382:microbiology*; D014416:Tunisia
chemical_list: D000975:Antioxidants; D002338:Carotenoids